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Abstract:

The present invention is directed to polyamides that are crosslinkable in
the presence of water having desirable properties including long open
time, good adhesion and cold flexibility. Notably, the polyamides of the
present invention are suitable for structural and semi-structural bonding
applications utilizing a hot melt process, roll coater or bead extrusion
process.

Claims:

1. A process for producing a hot melt composition comprising a polyamide
obtained by polycondensation of: (i) an acid component comprising at
least one dimerized C12 to C24 unsaturated fatty acid; (ii) at
least one C6 to C22 aliphatic dicarboxylic acid; (iii) an amine
component comprising at least one C6 to C22 alkylene diamine;
(iv) at least one heterocyclic secondary diamine; and (v) at least one
polyoxyalkylenediamine.

2. The process of claim 1, wherein the acid component further comprises
at least one monomer fatty acid.

4. The process of claim 1, wherein at least one polyoxyalkylenediamine is
a polyether-based diamine having an approximate molecular weight in the
range of 300 to 2000 daltons and having the structure
H2N--R1--O--(R2O)x-R3--NH2 wherein R1,
R2 and R3 are C1-C4 alkyl and x is 5 to 34.

5. The process of claim 1, wherein the acid component to the amine
component is in a ratio of about 0.7:1 to about 1:0.8.

6. A process for producing a moisture-curable hot melt composition
comprising reacting: (i) the polyamide of claim 1; and (ii) a
functionalized alkoxysilane under conditions resulting in attachment of
di-alkoxysilane or tri-alkoxysilane terminal groups to the polyamide.

7. The process of claim 6, wherein the functionalized alkoxysilane
component to the polyamide component is in a molar ratio of about 0.8:1
to about 2:1.

8. The process of claim 6, wherein the amount of functionalized
alkoxysilane component reacted is in an amount greater than 1 equivalent
but less than 2 equivalents relative to the polyamide.

9. The process of claim 6, wherein the functionalized alkoxysilane is an
isocyanate-functional alkoxysilane, an epoxide-functional alkoxysilane or
a chloromethylphenyl-functional alkoxysilane.

10. The hot melt composition formed by the process of claim 1.

11. The moisture-curable hot melt composition produced by the process of
claim 6.

12. The moisture-curable hot melt composition of claim 11 having an open
time of at least 90 seconds.

13. The moisture-curable hot melt composition of claim 11 having a
viscosity at 350.degree. F. and 1 atmosphere pressure in the range of
about 10 P to about 190 P.

14. The moisture-curable hot melt composition of claim 11 having a
softening point of 125.degree. C. or less.

15. The moisture-curable hot melt composition of claim 11 having a curing
time of at least 7 days.

16. The moisture-curable hot melt composition of claim 11 having a
mechanical strength of at least 31 MPa as measured using ASTM Standard D
638-00.

17. The moisture-curable adhesive composition of claim 11 having an
elongation of at least 40% as measured using ASTM Standard D 638-00.

18. The moisture-curable adhesive composition of claim 11 having an
ultimate tensile break of at least 180 psi.

19. The moisture-curable adhesive composition of claim 11 having a yield
point of at least 290 psi.

20. The hot melt composition formed by the process of claim 1 further
comprising one or more additives.

21. An article comprising a first substrate joined to a second substrate
by an adhesive comprising the hot melt composition of claim 1.

22. The article of claim 21 wherein at least one substrate is paper,
plastic or wood.

23. A method of bonding a first substrate to a second substrate
comprising applying the moisture-curable hot melt composition of claim 11
to a surface of said first substrate to form a coating on said surface,
contacting said surface having the coating with a surface of said second
substrate and permitting the moisture-curable hot melt composition to
moisture-cure.

24. The method of claim 23 further including the step of heating the
moisture-curable hot melt composition to make it flowable prior to
applying.

25. The method of claim 24, wherein said applying is by means of bead
extrusion.

26. A method of providing a moisture-curable coating to a substrate
comprising: (a) providing the moisture-curable hot melt composition of
claim 11; (b) heating said moisture-curable hot melt composition to a
flowable state; (c) applying said moisture-curable hot melt composition
to a substrate surface to form a coating; (d) permitting said coating to
moisture-cure.

27. The method of claim 26 wherein said applying is by means of a roller
applicator.

Description:

FIELD OF THE INVENTION

[0001] The present invention is directed to polyamides that are
crosslinkable in the presence of water having desirable properties
including long open time, good adhesion and cold flexibility. Notably,
the polyamides of the present invention are suitable for structural and
semi-structural bonding applications utilizing a hot melt process, roll
coater or bead extrusion process.

BACKGROUND OF THE INVENTION

[0002] Currently available polyamides that are crosslinkable in the
presence of water have a short open time that is not amenable for roll
coater application. Thus, there is a need for polyamides that have a
sufficiently long open time suitable for bonding applications utilizing a
roll coater or bead extrusion process. In addition, there is a need for
polyamides which exhibit desirable thermomechanical properties following
crosslinking upon exposure to moisture.

SUMMARY OF INVENTION

[0003] In one aspect of the invention, there is provided polyamides that
are crosslinkable in the presence of water having desirable properties
including long open time, good adhesion and cold flexibility as well as
methods for using the same. Advantageously, the compositions are suitable
as adhesives for structural and semi-structural bonding applications
utilizing a roll coater or bead extrusion process.

[0004] In another aspect of the invention, there is provided processes for
producing a hot melt composition including a polyamide obtained by
polycondensation of: (i) an acid component including at least one
dimerized C12 to C24 unsaturated fatty acid; (ii) at least one
C6 to C22 aliphatic dicarboxylic acid; (iii) an amine component
including at least one C6 to C22 alkylene diamine; (iv) at
least one heterocyclic secondary diamine; and (v) at least one
polyoxyalkylenediamine.

[0005] In addition, in one aspect of the invention, there is provided hot
melt compositions produced by the aforementioned processes.

[0006] In one aspect of the invention, there is provided articles
including a first substrate joined to a second substrate by an adhesive
including a hot melt composition of the present invention.

[0007] The invention also provides processes for producing a
moisture-curable hot melt composition including reacting: (i) the
aforementioned polyamide; and (ii) a functionalized alkoxysilane under
conditions resulting in attachment of di-alkoxysilane or tri-alkoxysilane
terminal groups to the polyamide.

[0008] In another aspect of the invention, there is provided
moisture-curable hot melt compositions produced by the aforementioned
processes.

[0009] In addition, there is provided methods of bonding a first substrate
to a second substrate including the steps of applying a moisture-curable
hot melt composition of the present invention to a surface of said first
substrate to form a coating on said surface, contacting said surface
having the coating with a surface of said second substrate and permitting
the moisture-curable hot melt composition to moisture-cure.

[0010] In yet another aspect of the present invention, there is provided
methods of providing a moisture-curable coating to a substrate including
the steps of: (a) providing a moisture-curable hot melt composition of
the present invention; (b) heating said moisture-curable hot melt
composition to a flowable state; (c) applying said moisture-curable hot
melt composition to a substrate surface to form a coating; (d) permitting
said coating to moisture-cure.

DETAILED DESCRIPTION

[0011] As used herein, the phrase "open time" with reference to an
adhesive of the present invention refers to the time, after initial
application, during which the adhesive can still wet out a second
substrate.

[0012] As used herein, the term "curing time" with reference to an
adhesive of the present invention refers to the time during which the
polyamide crosslinks after being stored under specific conditions.

[0013] As used herein, the term "set time" refers to a time prior to fully
curing associated with a surface cure which no longer wets out or is
tacky to the touch. Generally, the green strength of an adhesive is
measured at the set time.

[0014] As used herein, the term "green strength" refers to the ability of
an adhesive to hold two surfaces together when first contacted and before
the adhesive develops its ultimate bonding properties when fully cured.
The degree of green strength exhibited by an adhesive is very important
in many applications. High green strength adhesives tend to prevent
wrinkling and slippage of films during lamination. In panel assembly and
packaging, faster handling and wrapping rates can be achieved with such
high green strength adhesives. When adhesives are applied to a vertical
surface, a sufficiently high green strength allows the adhesive to
prevent a mechanically unsupported, bonded member from slipping under the
influence of gravity. When employed for flocking, a high green strength
adhesive holds the fibers in place while curing. Also, in the laying of
carpet or synthetic flooring, adhesives having a high green strength
resist curling due to the shape memory of the flooring which is acquired
when stored in a roll.

[0015] The polyamides of the present invention are cured in the presence
of humidity after a defined time which varies according to the nature of
the crosslinkable polyamide. One skilled in the art will understand that
the presence and degree of crosslinking, i.e., the crosslink density, can
be determined by a variety of methods, such as dynamic mechanical thermal
analysis (DMA) using a TA Instruments DMA 2980 DMA analyzer over a
temperature range of -65° F. (-18° C.) to 350° F.
(177° C.) conducted under nitrogen according to ASTM D 4065-01.
This method determines the glass transition temperature and crosslink
density of free films of coatings or polymers. These physical properties
of a cured material are related to the structure of the crosslinked
network.

[0016] The polyamides of the present invention are useful as laminating or
structural adhesives suitable for use in plastics, appliances, furniture,
bookbinding, woodworking as well as other industrial applications
requiring structural or semi-structural binding.

[0017] Additionally, the polyamides of the present invention are useful in
applications including sealants, caulk, plastics and other materials.

[0018] The polyamides of the present invention may be applied utilizing a
reactive hotmelt process, roll coater or bead extrusion process.

[0019] In certain embodiments of the present invention, there is provided
articles including a first substrate joined to a second substrate by an
adhesive including a hot melt composition of the present invention
wherein at least one substrate is paper, plastic or wood.

[0020] In certain embodiments of the present invention, there is provided
methods of bonding a first substrate to a second substrate including the
steps of heating a moisture-curable hot melt composition of the present
invention to make it flowable prior to applying, applying the
moisture-curable hot melt composition of the present invention to a
surface of said first substrate to form a coating on said surface,
contacting said surface having the coating with a surface of said second
substrate and permitting the moisture-curable hot melt composition to
moisture-cure.

[0021] In one embodiment, methods of the present invention apply the
moisture-curable hot melt compositions by means of bead extrusion. In
another embodiment, methods of the present invention apply the
moisture-curable hot melt compositions by means of a roller applicator.

Polyamides

[0022] Polyamides of the present invention are formed from
polycondensation of a) an acid component including at least one dimerized
C12 to C24 unsaturated fatty acid, at least one C6 to
C22 aliphatic dicarboxylic acid; and b) an amine component including
at least one C6 to C22 alkylene diamine, at least one
heterocyclic secondary diamine and at least one polyoxyalkylenediamine.
An overbalance of amine component results in an amine terminated
polyamide which has a desirable combination of thermomechanical
properties including long open time, good adhesion and cold flexibility.

[0023] In certain embodiments, the acid component further comprises at
least one monomer fatty acid.

[0025] In certain embodiments, at least one polyoxyalkylenediamine is a
polyether-based diamine having an approximate molecular weight in the
range of 300 to 2000 daltons and having the structure
H2N--R1--O--(R2O)x-R3--NH2 wherein R1,
R2 and R3 are C1-C4 alkyl and x is 5 to 34.

[0026] In certain embodiments, the acid component to the amine component
is in a ratio of about 0.7:1 to about 1:0.8.

[0027] Furthermore, the resultant aminofunctional polyamides may be
reacted with a functionalized alkoxysilane under conditions resulting in
attachment of di-alkoxysilane or tri-alkoxysilane terminal groups to the
polyamide. This modification to the polyamide imparts the property of
moisture curability thereto.

[0028] In certain embodiments, the functionalized alkoxysilane component
to the polyamide component is in a molar ratio of about 0.8:1 to about
2:1.

[0029] In certain embodiments, the amount of functionalized alkoxysilane
component reacted is in an amount greater than 1 equivalent but less than
2 equivalents relative to the polyamide.

[0030] In certain embodiments, the functionalized alkoxysilane is an
isocyanate-functional alkoxysilane, an epoxide-functional alkoxysilane or
a chloromethylphenyl-functional alkoxysilane.

[0031] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have an open time of at least 90 seconds. In
certain embodiments, the moisture-curable hot melt compositions of the
present invention have an open time of at least 2 minutes. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have an open time of about 2 minutes to about 6 minutes. In
certain embodiments, the moisture-curable hot melt compositions of the
present invention have an open time of about 4 minutes. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have an open time of up to 8 minutes.

[0032] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a viscosity at 350° F. and 1
atmosphere pressure in the range of about 10 P to about 190 P. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have a viscosity at 350° F. and 1 atmosphere pressure in
the range of about 10 P to about 60 P. In certain embodiments, the
moisture-curable hot melt compositions of the present invention have a
viscosity at 350° F. and 1 atmosphere pressure of about 10 P to
about 30 P. In certain embodiments, the moisture-curable hot melt
compositions of the present invention have a viscosity at 350° F.
and 1 atmosphere pressure of about 16 P.

[0033] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a softening point of 125° C. or
less. In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a softening point of at least 110°
C. In certain embodiments, the moisture-curable hot melt compositions of
the present invention have a softening point of at least 115° C.
In certain embodiments, the moisture-curable hot melt compositions of the
present invention have a softening point in the range of about
110° C. to about 120° C.

[0034] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a curing time of at least 7 days. In
certain embodiments, the moisture-curable hot melt compositions of the
present invention have a curing time of at least 9 days. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have a curing time of at least 14 days. In certain embodiments,
the moisture-curable hot melt compositions of the present invention have
a curing time in the range of about 7 days to about 21 days. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have a curing time of about 7 days to about 28 days.

[0035] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a mechanical strength of at least 31 MPa as
measured using ASTM Standard D 638-00. In certain embodiments, the
moisture-curable hot melt compositions of the present invention have a
mechanical strength of at least 34 MPa as measured using ASTM Standard D
638-00. In certain embodiments, the moisture-curable hot melt
compositions of the present invention have a mechanical strength of at
least 54 MPa as measured using ASTM Standard D 638-00. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have a mechanical strength in the range of about 34 MPa to
about 74 MPa as measured using ASTM Standard D 638-00. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have a mechanical strength of up to about 86 MPa as measured
using ASTM Standard D 638-00.

[0036] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have an elongation of at least 40% as measured
using ASTM Standard D 638-00. In certain embodiments, the
moisture-curable hot melt compositions of the present invention have an
elongation in the range of about 80% to about 200% as measured using ASTM
Standard D 638-00. In certain embodiments, the moisture-curable hot melt
compositions of the present invention have an elongation of about 130% as
measured using ASTM Standard D 638-00. In certain embodiments, the
moisture-curable hot melt compositions of the present invention have an
elongation in the range of about 80% to about 290% as measured using ASTM
Standard D 638-00. In certain embodiments, the moisture-curable hot melt
compositions of the present invention have an elongation of up to about
300% as measured using ASTM Standard D 638-00.

[0037] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have an ultimate tensile break of at least 180
psi. In certain embodiments, the moisture-curable hot melt compositions
of the present invention have an ultimate tensile break of at least 310
psi. In certain embodiments, the moisture-curable hot melt compositions
of the present invention have an ultimate tensile break in the range of
about 310 psi to about 610 psi. In certain embodiments, the
moisture-curable hot melt compositions of the present invention have an
ultimate tensile break of about 460 psi. In certain embodiments, the
moisture-curable hot melt compositions of the present invention have an
ultimate tensile break of up to about 780 psi.

[0038] In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a yield point of at least 290 psi. In
certain embodiments, the moisture-curable hot melt compositions of the
present invention have a yield point in the range of about 290 psi to 490
psi. In certain embodiments, the moisture-curable hot melt compositions
of the present invention have a yield point of about 390 psi. In certain
embodiments, the moisture-curable hot melt compositions of the present
invention have a yield point of up to 600 psi.

Acid Component

[0039] Suitable dimerized C12 to C24 unsaturated fatty acids for
use in the present invention include but are not limited to a dimer acid
mixture with approximately 94% high dibasic acid content (e.g.,
Empol® 1061 having approximately 3.5% monobasic acid, approximately
94% dibasic acid, and approximately 2.5% polybasic acid, commercially
available from Cognis, Monheim, Germany).

[0040] Suitable C6 to C22 aliphatic dicarboxylic acids for use
in the present invention include but are not limited to sebacic acid,
azelaic acid, stearic acid, and mixtures of two or more thereof. In
certain embodiments, the compositions of the present invention include
sebacic acid and stearic acid.

[0041] Sebacic acid is a C10 dicarboxylic acid having the structure
(HOOC)(CH2)8(COOH) that is derived from castor oil (e.g.,
commercially available from Arizona Chemical, Jacksonville, Fla., United
States).

[0042] Azelaic acid is a C9 dicarboxylic acid (also known by the
Chemical Abstract Index Name nonanedioic acid) having the structure
HO2C(CH2)7CO2H that occurs naturally in wheat, rye,
and barley and is also naturally produced by Malassezia furfur (also
known as Pityrosporum ovale) (e.g., Emerox® 1144, commercially
available from Cognis, Monheim, Germany).

[0043] Stearic acid is a C18 dicarboxylic acid having the structure
C18H36O2, or CH3(CH2)16COOH that occurs in
many animal and vegetable fats and oils (e.g., commercially available
from Cognis, Monheim, Germany).

[0044] Suitable monomer fatty acids for use in the present invention
include but are not limited to PRIFRAC 2980, RESINOLINE BD2, TOFA and
mixtures thereof.

[0045] Tall Oil Fatty Acid (TOFA) is a mixture of volatile fatty acids
having a rosin content of 1-10% (e.g., commercially available from MWV,
Glen Allen, Va., United States).

[0046] PRIFRAC 2980 is a C18 monoacid (e.g., commercially available
from Unichema North America, Chicago, Ill., United States).

[0047] RESINOLINE BD2 is a fatty acid of wood oil at 2% max of resinic
acid (e.g., commercially available from DRT-GRANEL, Pax, France).

Amine Component

[0048] Suitable amines for use in the present invention include but are
not limited to ethylenediamine (EDA), hexamethylenediamine (HMDA),
piperazine (PIP), polyoxyalkylenediamine is a polyether-based diamine
having an approximate molecular weight in the range of 300 to 2000
daltons and having the structure
H2N--R1--O--(R2O)x-R3--NH2 wherein R1,
R2 and R3 are C1-C4 alkyl and x is 5 to 34 and
mixtures of two or more thereof. In certain embodiments, the compositions
of the present invention include piperazine, Jeffamine D400 and Jeffamine
D2000.

[0049] Ethylenediamine having the formula C2H4(NH2)2
is manufactured by reacting ammonia and 1,2-dichloroethane (e.g.,
commercially available from Huntsman, Salt Lake City, Utah, United
States).

[0050] Hexamethylenediamine (HMDA) having the formula
H2N(CH2)6NH2 may be manufactured by hydrogenation of
adiponitrile (e.g., commercially available from Sigma-Aldrich Company
Ltd., St. Louis, Mo., United States).

[0051] Piperazine is an organic compound that consists of a six-membered
ring containing two opposing nitrogen atoms having the formula
C4H10N2 (e.g., commercially available from Orchid Chemical
Supplies, Ltd., Hangzhou, China).

[0052] Suitable polyoxyalkenediamines include, but are not limited to,
polyoxyalkylenediamine is a polyether-based diamine having an approximate
molecular weight in the range of 300 to 2000 daltons and having the
structure H2N--R1--O--(R2O)x-R3--NH2 wherein
R1, R2 and R3 are C1-C4 alkyl and x is 5 to 34
(JEFFAMINE® commercially available from Huntsman, Salt Lake City,
Utah, United States). In certain embodiments, at least one
polyoxyalkenediamine is JEFFAMINE® D-400 and/or JEFFAMINE®
D-2000.

Silane Component

[0053] Suitable silane components for use in the present invention include
but are not limited to isocyanate-functional alkoxysilane,
epoxide-functional alkoxysilane, chloromethylphenyl-functional
alkoxysilane and mixtures of two or more thereof.

[0054] Examples of functionalized silane components include, but are not
limited to gamma-glycidoxypropyltrimethoxysilane (e.g., commercially
available from Power Chemical Corp., Jiangsu, China),
((chloromethyl)phenylethyl)trimethoxy-silane (e.g., commercially
available from ChemPacific Corp., Baltimore, Md., United States), and
gamma-glycidoxypropylmethyldimethoxysilane (e.g., commercially available
from Power Chemical Corp., Jiangsu, China).

Additive Component

[0055] One or more additive components may optionally be added to the
polyamides of the present invention and include but are not limited to
conventional additives including antioxidants (e.g., Ciba®
Irganox® 1010 (commercially available from CIBA Specialty Chemicals,
Inc., Basel, Switzerland), pigments, anti-azurants, accelerators,
stabilizers, plasticizers, and tackifying resins. Such additives are
known to the person skilled in the art.

[0056] In certain embodiments, one or more additive components do not
significantly impact the thermomechanical properties of the polyamide.

[0057] In certain other embodiments, one or more additives impact one or
more properties of the polyamide (e.g. open time, green time, curing
time, or any thermomechanical property thereof including viscosity,
softening point, or mechanical strength after curing).

Process for Making Polyamides

[0058] Polyamides of the present invention may be synthesized by the
following process.

[0062] The resultant composition may be poured into suitable packaging for
distribution. Note that the composition may be partially cured at the
time of packaging under the effect of moisture from the packaging and/or
the environment.

[0063] Exemplary polyamides of the present invention set forth in Tables
1-5 below were prepared by mixing the reactant components, recited
therein in parts by equivalent, heating the blended materials for 90 min.
under nitrogen at 227° C. followed by an additional 60 min. under
vacuum at 227° C. to obtain the polyamide. The temperature was
subsequently lowered to 177° C. and silane was charged dropwise
under nitrogen by the aid of a dropping funnel. The mixture was stirred
at this temperature for 60 min. and for an additional 2 min. under vacuum
to obtain a bubble-free, moisture curable polyamide.

[0064] The invention may be further understood with reference to the
following non-limiting examples.

[0066] The crosslinkable polyamides were cured under ambient atmospheric
conditions. Various properties of the compositions were evaluated
following curing. Specifically, test samples of the composition were
subjected to various test methods to determine characteristics of the
composition including ASTM D 3236-88 (Brookfield spindle 27; 10 g sample
in a viscometer-tube conditioned for 10 min at 350° F. under
nitrogen and a reading taken following such treatment) for determining
viscosity, ASTM E 28-99 (molten polyamide was poured onto a ring and
checked after 2-3 hrs with Ring and Ball instrument) for determining
softening point (SP), ASTM D 638-00 (cut macro dogbones and micro
dogbones from a 50 mil plaque and tensile run after curing time) for
determining tensile strength and molten polyamide from a viscometer tube
at 350° F. poured onto a cardboard using a 10 mil draw down bar
with the time checked every 30 seconds for determining open time. In
particular, the following properties were determined using the
aforementioned methods: viscosity, softening point, tensile strength (AV,
AmV, 2% modulus, % elongation, ultimate tensile break and yield point),
open time and curing time. Results of the inventive compositions of
Tables 1-5 are detailed below in Tables 6-10, respectively.

[0067] As reflected in the examples of the present invention provided,
polyamides of the present invention exhibit desirable thermomechanical
properties following crosslinking upon exposure to moisture. In general,
increased open time and mechanical strength are diametrically opposed.
Surprisingly, the crosslinkable polyamides of the present invention
exhibited long open times while maintaining sufficient green strength to
result in a desirable final mechanical strength that is sufficient to
bind a particular substrate thereto.